by Bob Atkins
The Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) is a wideangle zoom lens designed for APS-C sensor cameras. That means just about everything except the Kodak full frame DSLRS and the Canon EOS 1D series DLSRs. On a typical APS-C digital camera, such as the Canon EOS 20D, it has the same field of view as a 17.6mm to 28.8mm lens would on a full frame 35mm camera. The lens is available in Canon EOS, Nikon AF-D and Konica-Minolta AF-D mounts.
Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) is a Tamron "Di (II)" lens. Di (II) lenses are designed with digital SLRs in mind and Tamron say that they have higher resolution, better control of flare and ghosting, less light fall-off and lower chromatic aberration than earlier designs.
Note that the SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) has APS-C frame 35mm coverage, signified by the Di-II designation. Like the Canon EF-S series lenses it's not designed to provide full frame coverage. While the Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) can be physically mounted on any EOS body (it has an EF mount, not an EF-S count), when used on a full frame body severe corner vignetting will be observed. In a brief viewfinder based test, I'd estimate that full frame coverage may be available between 14mm and 18mm. I did not test for image quality at the edges of the 35mm frame under these conditions.
I don't know the degree of coverage for the 1.3x sensor found in the Canon 1D/1DMkII. I'm pretty sure you would have vignetting at 11mm. Full frame coverage would probably start around 13mm (?), again though I don't know what frame edge image quality would be. The lens is not designed or specified for greater than APS-C sensor coverage.
|Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) SPECIFICATIONS|
|Angle of View
|103° - 75° diagonal
93° - 66° horizontal
70° - 46° vertical
|Lens Construction||15 elements in 12 groups|
|Minimum Focus Distance||0.25m (9.8") (throughout the entire zoom range)|
|Maximum Mag. Ratio||1:8|
|Overall Length||78.6mm (3.1")|
|Maximum Diameter||82.2mm (3.3"|
|Diaphragm Blade||7 blades|
|Minimum Aperture||F/22 - F/29|
|Standard Accessory||Flower-shaped Lens Hood|
|Compatible Mount||Canon AF, Konica Minolta AF-D and Nikon AF-D|
The lens solidly constructed with a low reflectivity black finish and rubberized zoom and focus controls. It comes with a "petal" style detachable lenshood which is optimized for the lens coverage on an APS-C sensor. If the lens is mounted on a full frame DSLR, not only do you see corner vignettting at 11mm, but you also see vignetting at the top, bottom and sides of the frame when the lens hood is mounted. The barrel material appears to be plastic.
The zoom cannot be locked, but I saw no "creep" at any focal length setting, even with the lens pointing vertically up or down.
For a wide zoom the Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) is fairly compact. Above you can see it compared to the Canon EF28-105/3.5-4.5 USM.
Focus can be switched between AF and MF with a small switch on the left, near the lens mount. Manual focus is smooth but underdamped with about a 90 degree rotation of the rubberized focus ring from 0.25m to infinity. There are no depth of field scales and no IR focus identification mark. It's marked with focal lengths of 11mm (maximum aperture f4.0 ), 13mm (maximum aperture f4.5), 15mm (maximum aperture f5.0) and 18mm (maximum aperture f5.6). The mimumum aperture is f22 at 11mm, 13mm and 15mm and f29 at 18mm.
The Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) takes a 77mm diameter filter. No vignetting was observed when using a standard thickness Tiffen circular polarizer. It appears that thin filters are not required with this lens (unless filters are stacked, which is not a recommended practice on any lens). Despite the 77mm filter size, the actual exposed diameter of the front element is 44mm, so a 77mm filter gives plenty of clearance, even with the lens at 11mm (103 degree field of view).
Focus speed is pretty good. It takes the Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) around 0.5 seconds to go from infinity to 0.25m. Focusing isn't silent but it's not really noisy and certainly not a problem.
The lens extends slightly (by about 0.4cm) when zoomed, but does not change length on focusing (it's internal focus - IF) and the front of the barrel does not rotate when the lens is zoomed or focused. However the focus ring does spin during autofocus, so keep your hands away from it.
Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) Optical Construction
The Tamron SP AF11-18mm F/4.5-5.6 Di-II LD Aspherical (IF) uses several types of special optical elements as shown above. Aspherical elements are used to minimize aberrations like spherical aberration which become troublesome in fast wideangle lenses.
The lens has a close focus distance of 0.25m at all focal lengths, which gives a maximum magnification of 1:8 at 18mm.
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